In a forest, there are at least five FSMO roles that are assigned to one or more domain controllers. The five FSMO roles are:
Schema Master: The schema master domain controller controls all updates and modifications to the schema. To update the schema of a forest, you must have access to the schema master. There can be only one schema master in the whole forest.
Domain naming master: The domain naming master domain controller controls the addition or removal of domains in the forest. There can be only one domain naming master in the whole forest.
Infrastructure Master: The infrastructure is responsible for updating references from objects in its domain to objects in other domains. At any one time, there can be only one domain controller acting as the infrastructure master in each domain.
Relative ID (RID) Master: The RID master is responsible for processing RID pool requests from all domain controllers in a particular domain. At any one time, there can be only one domain controller acting as the RID master in the domain.
PDC Emulator: The PDC emulator is a domain controller that advertises itself as the primary domain controller (PDC) to workstations, member servers, and domain controllers that are running earlier versions of Windows. For example, if the domain contains computers that are not running Microsoft Windows XP Professional or Microsoft Windows 2000 client software, or if it contains Microsoft Windows NT backup domain controllers, the PDC emulator master acts as a Windows NT PDC. It is also the Domain Master Browser, and it handles password discrepancies. At any one time, there can be only one domain controller acting as the PDC emulator master in each domain in the forest.
You can transfer FSMO roles by using the Ntdsutil.exe command-line utility or by using an MMC snap-in tool. Depending on the FSMO role that you want to transfer, you can use one of the following three MMC snap-in tools:
Active Directory Schema snap-in
Active Directory Domains and Trusts snap-in
Active Directory Users and Computers snap-in
If a computer no longer exists, the role must be seized. To seize a role, use the Ntdsutil.exe utility.
For additional information about how to use the Ntdsutil.exe utility to seize FSMO roles, click the article number below to view the article in the Microsoft Knowledge Base:
255504 Using Ntdsutil.exe to Seize or Transfer the FSMO Roles to a Domain